The aerosol High Dilution System HDS 561 for particle measuring devices is characterized by its very wide, variable range of dilution ratios (up to 1:100’000). The volume flow rate setting is factory-provided and made custom-specific. These features eliminate the need for cascading multiple dilution systems and reduces the system pressure loss. The possibility of remote checking and control of dilution ratio expands its application fields, as there are e.g. dilution of aerosols for measurement with particle counters, defined supply of a source strength with aerosol generators. The applied HEPA-filter system guaranties long lifetime and state of readiness.
The operating principle is based on the splitting of the total volume flow into a so-called bypass volume flow and a capillary volume flow. By means of an HEPA-filter all the particles are removed from the substantially larger bypass volume stream. The particle concentration of the smaller capillary volume stream remains unchanged. These two flows are eventually brought together again. The dilution factor is determined by the ratio of the capillary volume flow to the total volume flow.